It is the gravy train none can afford to miss. When Delia Smith makes her long-awaited return this week, nervous food producers everywhere will be watching intently. Gaining her blessing is akin to a royal patronage, and a vast marketing machine is already working to ensure that the celebrated 'Delia effect' will be felt in millions of pounds at the tills.

Smith's first book for five years, already a bestseller even before it is published, will recommend dozens of products, including specific brands, for making fast and easy meals. Demand for these foods and kitchen utensils is expected to soar overnight, such is Smith's record of making or breaking reputations and shaping the nation's shopping habits.

For food companies, inclusion in Delia's How to Cheat at Cooking is likely to mean the kind of publicity that money can't buy, prominent display on the retail shelf and previously unimagined profits. For supermarkets, the opportunity to cash in on reflected glory is unmissable. Smith, a multi-millionaire, has a Midas touch which can transform a business's fortunes. Among those anointed by her new book is Fratelli Camisa, an Italian fine food supplier, for its martelli pasta. Seasoned Pioneers, founded on Merseyside in 1999, is celebrating after Smith handpicked 10 of its spices and seasonings including Moroccan ras-el-hanout, Goan xacuti and African tsire powder.

The 140 'easy recipes' are being released gradually as part of strategy to generate maximum publicity for Smith's comeback from retirement. The 66-year-old, whose books have sold 19 million copies, is aiming to regain her home-cooking crown from younger rivals such as Nigella Lawson and Jamie Oliver, who was not even born when she began her career.

The term 'Delia effect' entered the Collins English Dictionary in 2001. The phenomenon was evident when she was seen using cranberries on TV and, a day later, sales rose by 200 per cent. Her demonstration of how to fry and boil eggs properly saw sales climb by 54 million. Demand for salted capers rose by 350 per cent and dates by 35 per cent when she praised them in the first How To Cook series. And when she described a 10-inch metal pan as 'a little gem which will serve you for a lifetime of omelette-making', it rescued the struggling Lancashire firm which had been selling only 200 of the pans a year. Lune Metal Products had to take on extra staff to make 90,000 new pans in just four months.

Since then the 'Delia effect' has been shorthand for a celebrity endorsement that prompts a shopper stampede. Sales of goose fat rocketed when the product was championed by Lawson as the essential Christmas cooking ingredient. Purchases of asparagus shot up after being featured in Oliver's TV adverts, while Gordon Ramsay's cooking of tripe boosted sales by 400 per cent. Beyond the kitchen, Richard and Judy's book club has become integral to the bestseller lists.

How to Cheat at Cooking marks Smith's comeback after stepping out of the limelight in 2005. The book is a return to her very first, which in 1971 had the same title and was aimed at people who didn't have time to cook, but has been updated for the stressed modern consumer struggling to feed their family.

Due to be published by Random House's Ebury Press on Friday, it is already number six in the online retailer Amazon's cookbook chart, based on pre-orders alone. Waterstone's said that

pre-orders were outstripping those received for Oliver's most recent book, Jamie at Home, and were the greatest in any category since Harry Potter and the Deathly Hallows

Glen Holmes, the book chain's cookery buyer, said: 'Waterstone's expects Delia to take back her crown with gusto, with huge sales for the book on release then a return to the top of the charts at Christmas - it will sell more than half a million copies this year.'

Joel Rickett, deputy editor of the Bookseller, said: 'It will be everywhere marketing-wise. It's not something dreamt up by a publicist - she's going into this with all guns blazing. She names particular products and the supermarkets have been scrambling for the ingredients. It will put huge pressure on producers - there's going to be a pitta bread maker somewhere absolutely besieged.'

The media campaign has supermarkets, TV, radio, magazines, newspapers and the internet feeding off one another. Smith has been working with several supermarkets where copies of the book are expected to be sold at a discount from stands alongside some of her favoured products. Interviews with the cook will appear in Asda Magazine, Sainsbury's Magazine and Waitrose Food Illustrated. There will also be interviews in Observer Food Monthly, GQ and Radio Times among others, and on radio and TV.

Smith will also return to television with another series of her own, expected in the spring, although the BBC is not allowed to promote commercially branded products. The programme will feature cooking, along with other aspects of her life such as football and her devout Catholicism.

Celebrity chef Antony Worrall Thompson said: 'I guess she will be as popular as ever. She has this amazing power and good luck to her. Nigella's got the top end of the market but Delia is very much Middle Britain and has an affinity with the public. She's the goddess of TV cooks and if she was up for election, I'm sure she'd be Prime Minister.'